As areas where users are located become wider and wider, remote base stations have gradually evolved from conventional macro base stations to distributed remote base stations. With regard to distributed remote base stations, a common public radio interface (CPRI) data connection is achieved between a remote radio unit (RRU) and a baseband unit (BBU) by using direct driving through an optical fiber.
As remote base stations are developing toward a cloud radio access network, BBUs are centralized on scale to form a baseband unit pool (BBU pool) and RRUs of multiple remote base stations share BBU resources, where the remote base stations are geographically distributed. As shown in FIG. 1, each remote base station is connected to a BBU through one optical fiber or one pair of optical fibers and data is transmitted in a point-to-point manner, which requires a large amount of optical fibers.